Item data structure (Generation III)

Item data is stored in a 44-byte structure in the US version of the GBA games.

Offset	Field	Size
0	Name	14 bytes
14	Index number	2 bytes
16	Price	2 bytes
18	Special value 1	1 byte
19	Special value 2	1 byte
20	Description pointer	4 bytes
24	Mystery value	2 bytes
26	Pocket	1 byte
27	Type	1 byte
28	Pointer to field usage code	4 bytes
32	Battle usage	4 bytes
36	Pointer to battle usage code	4 bytes
40	Extra parameter	4 bytes

Pocket

This determines which pocket of the bag the item should be stored in.

Number	Item type
1	Main pocket
2	Poké Ball
3	Berries
4	TMs and HMs
5	Key items

Type

For items other than Poké Balls, the type determines how the item can be used. With Poké Balls, the type indicates the Poké Ball type, and is one less than the index number.

Type	Description
0	Mail
1	Items which can be used out-of-battle.
2	Items which must be used in a certain location; key items of this type can be assigned to select.
3	Only the Pokéblock case is of this type.
4	Items which cannot be used out-of-battle.

Mystery values

Mystery value 1 is:

• 0 for normal items.
• 1 for HMs and most key items.
• 2 for some plot-related key items: Devon Goods, Letter, Red Orb, Blue Orb and Oak's Parcel.

Mystery value 2 is:

• 0 for most items.
• 1 for many key items: Mach Bike, Itemfinder, Old Rod, Good Rod, Super Rod, Acro Bike, Pokéblock Case, Bicycle, Town Map, VS Seeker, Fame Checker, TM Case, Berry Pouch, Teachy TV, Tri-Pass, Rainbow Pass, Tea, Mysticticket, Auroraticket, Powder Jar, Ruby, Sapphire, Magma Emblem and Old Sea Map.

Battle usage

Battle usage can be:

• 0 if the item can't be used in battle at all.
• 1 if the item's effect is seen during battle but on a subscreen, such as healing items.
• 2 if the item's effect is seen in battle such as Poké Balls.

Extra parameter

Extra parameter is used to distinguish Poké Balls and Mails, as opposed to just using the item index.